The present invention relates to an abrasiveness test for paper and other sheet materials. More specifically, the present invention relates to a method and device for measuring the abrasiveness of paper and other sheet materials by measuring the change in force required to punch the material.
Several different abrasion tests have been proposed and are currently in use for testing the abrasion resistance of paper. For example, there is a mechanical xe2x80x9cwet thumbxe2x80x9d test which rubs the surface of the paper, giving the wet abrasion resistance of the paper and a numerical evaluation of the wet abrasion resistance of the paper. This test is particularly important in relation to papers such as blueprint, cartographic papers, or any paper that is handled and used while wet.
Another abrasion test for paper is the Taber Abraser, which is used for testing both wet and dry paper. This apparatus uses a horizontal motor driven turntable to which the specimen is attached and a special wheel with embedded abrasive particles that rotate on the specimen. The abraded material is removed by suction and is weighed. The weight of the abraded material, called xe2x80x9cAbrasion Lossxe2x80x9d is a measure of the abrasion characteristics of the paper.
Another test draws an eraser over the surface of the paper and measures the number of passes necessary to wear a hole. This is particularly important for writing papers that must tolerate erasures without impairing the surface characteristics.
The Bekk Test is used to predict the wear imparted to printing surfaces by heavily loaded papers (papers with very high filler content) or papers that liberate mineral dust, when in use. This test measures abrasion by drawing a strip of paper through a distance of 10 cm between a glass plate and a rotating roller which hold the paper in contact with the glass at a pressure of 1 kg/sq. cm. of width of strip. Very fine scratches produced on the surface of the glass are counted and measured under a microscope. The results obtained are used to predict the wear characteristics of the paper on printing plates.
The knife-edge abrasion test, as taught in U.S. Pat. No. 3,827,281 to Hamel, is used to measure the abrasiveness of paper (and other sheet materials) by pressing a sharp but relatively easily dulled cutting edge onto a stack of paper. The pressure necessary to move the knife-edge through the layers relative to the depth of cut indicates the dulling of the knife. The abrasion characteristics of the paper are then calculated in relation to the rate of the dulling of the knife.
By far, the most widely used test for measuring dry abrasion due to paper is the needle penetration test or the sewing machine test developed by the Institute of Paper Chemistry (IPC) needle penetration test. This method involves puncturing a paper sample with a standardized bronze needle mounted on a sewing machine. The loss in weight of the needle after many (10,000 to 50,000) penetrations is used as a measure of the abrasive characteristics of the paper. This method has proved to be reliable for predicting the life of guillotine trimmer knives, and is sensitive enough to detect the effect of various additives and substrates.
The needle penetration test, however, has serious drawbacks. First, the weight loss during a test may range between 0 and about 1000 xcexcg, with 100 xcexcg being typical. With such a small change in weight, preparation and handling of the needle become critical, since small changes in weight can be introduced during handling or from paper debris. Second, the size of the paper sample to make 50,000 punches is considerable, and the test itself is time consuming. All these factors restrict the use of the needle penetration test to a clean laboratory.
Accordingly, there is still a need for a method and device for measuring the abrasiveness of paper and other sheet materials that is more accurate, more efficient and uses less material.
The present invention meets those needs by providing a device and a method for testing the abrasiveness of paper and other sheet materials that is less sensitive to operator error and environmental conditions and uses less material. The method uses the force required to punch through a material as the basis in determining the abrasiveness of the material, thereby alleviating the need to weigh the punching instrument and the need to calculate the rate of dulling of the punching instrument. The device maintains a continuous record of the force required to make a single punch in the material and maintains a continuous record of the unremitted force required to make a series of punches in the material. The record is then analyzed and the abrasiveness of the material is determined.
In accordance with one embodiment of the invention, a device for measuring abrasive properties of a material is provided comprising a punching module; a feed module for moving the material in relation to the punching module; a holding module that holds the material while the punching instrument penetrates the material, having a first position and a second position that couples to the feed module; and an instrument that records and analyzes the amount of the force needed to penetrate the material and calculates the abrasive properties of the material. The punching module comprises a punching instrument for punching the material, a driving mechanism for operating the punching instrument, and a measurement system that measures the amount of the force required to punch the material.
In accordance with another embodiment of the invention, a method for measuring abrasive properties of a material is provided comprising placing the material on a feed module, feeding the material relative to a punching module, holding the material stationary with a holding module, punching a material with the punching tool, measuring the amount of force necessary for the punching tool to punch the material, storing the force measurement for the punching tool to pierce the material, recording the force measurement that is stored, analyzing the force measurement, and determining the abrasiveness of the material.
Accordingly it is a feature of the invention to provide a device and method for measuring the abrasiveness of a material by measuring the amount of force necessary to punch a material. It is another feature of the invention to provide a device and method for measuring the abrasiveness of a material by measuring the amount of unremitted force necessary to make a series of punches in a material. Other features and advantages of the invention will be apparent from the following description, the accompanying drawings, and the appended claims.